About Betsey Dyer

Professor Betsey Dyer’s research interests include symbiosis; termite symbionts; evolution of cells; field microbiology; and genomics. She is part of Wheaton’s Genomics Research Group, which is working on regulatory sequences of the genomes of eukaryotes. Read more about her »

Professor of Biology Betsey Dyer says she won’t eat “presweetened cold cereals, especially of the sort that cause the milk to turn colors.” However, just about everything else (including termites) is on the menu for this adventuresome foodie and scientist who savors experimentation. Her stinky summer snack at the Oxford Symposium on Food and Cookery in England last summer is just one example.

When I wrote The Field Guide to Bacteria, I strived to acquire firsthand experience with everything I described. I went to Yellowstone for hot spring bacteria, Cape Cod for sulfur bacteria, termite hindguts for spirochetes, and on many more field trips and investigations. Some things were impossible at the time, such as a deep-sea dive in the Alvin submersible or a trip to the South Pole. However, for the chapters on fermented foods and drinks it seemed like a reasonable project to sample all that I wrote about. And mostly I did, including munsters, lambics, kvass and sour porridge.

A major exception was “surströmming.” I have always felt a bit guilty about the secondhand information that I included about this extraordinary fish delicacy. Surströmming, a specialty of northern Sweden, is one of the many fermented fishes that may be found in cuisines across Asia and northern Europe. The name means “sour herring.” However, this is no ordinary pickled herring, of which many varieties abound. Surströmming falls into such an extreme of fermentation that putrefied is a more appropriate word.

According to my description in The Field Guide to Bacteria (Cornell University Press, 2003), surströmming is an “extreme example of food enhanced by halophilic bacteria” and the flavor is “so extraordinary” that very little is exported, and only to certain Swedish expatriates. I wrote that a can of surströmming “bulges disconcertingly” because it is packed while still fermenting and producing odiferous gasses.

In July 2010, I was at the Oxford Symposium on Food, the topic of which was “Fermentation.” Renee Valeri (from southern Sweden) presented a paper on surströmming titled “A Preserve Gone Bad Or Just Another Beloved Delicacy?” Like many of the presenters, she promised a tasting at the end of her talk. Upon that announcement, a frisson went through the audience of 200 or so food enthusiasts (or “foodies”) who had traveled to the symposium from 26 different countries and who presumably were intrepid tasters of pretty much anything declared to be edible. In my immediate section, a whispered conference revealed that very few would be taking up Renee on her offer. Meanwhile, I was feeling a sort of dread at the opportunity at last to sample something I had written about. I knew enough about myself to know that I would be obliged to add that missing item in my repertoire of fermented cuisines.

But first was Renee’s talk, in which she revealed (and depicted) freshly caught (but soon rotten) herring during the year-and-a-half-long process of being putrefied to liquid and slime. Finally, just a hazy fish-like outline remains, composed almost entirely of bacteria and their wastes.

Herring is a staple in traditional Swedish cuisine and often the only protein by which Swedes of old times survived the winter. An abundant summertime catch of herring would be cause for celebration, but then how to preserve it for the long dark months ahead? Why not dry and salt it as many Scandinavians do? Apparently the climate of northern Sweden precludes efficient fish drying as well as sufficient salt production by evaporation. Only a tiny bit of salt could be added to the herring, and this served only to encourage specialized salt-loving “halophilic” bacteria to establish themselves in a roiling culture.

A can of surströmming

Wintertime hunger and most likely near starvation must have been the impetus for the rapid transition of attitudes of the northern Swedes. First, and very briefly, might have come disgust. But that would be quickly followed by gratitude for anything to eat at all in a snowbound and remote village. Finally (and probably soon after, given the human penchant for rationalization), came a sort of connoisseurship of the many nuanced variations of herring putrefication. Indeed, in some modern northern Swedish communities, late August still begins the surströmming celebrations. The European Union periodically tries to regulate and restrict this fermentation. Currently, it is legal to have cans of it, but people are no longer allowed to produce surströmming in wooden casks or by burying it (composting it, actually) in the ground.

Renee, by way of encouraging us to taste, reminded us that powerful off-putting odors (such as those of wonderful surface washed cheeses) often are accompanied by rich, delicious flavors. But she also provided many examples from the surströmming literature on the notorious nature of the putrid smell.

Renee’s talk ended; we could delay the tasting no longer. I began to justify in my mind not eating any. We were about to go to a Szechuan lunch, which was predicted to be exquisite, and I did not wish to destroy my palate. But then the tasting was postponed to tea time (4 p.m.), so I had the rest of the afternoon to think about it, during which time I (and others) wavered.

The can of surströmming, which bulged in a manner that should have made it illegal, was opened outdoors far from the building. Of the 200 symposium participants (all presumably great fans of fermentation), only about 25 got within wind of the table and of these only about a dozen gathered in close, snapping photos like paparazzi. However, few of those were actually planning to taste and gradually most backed away.

How to describe the smell? It was permeating and pervasive and so overloaded (or confused) the olfactory neurons that mine periodically (and deceptively) ceased to smell anything (as though acclimated). Then, a few seconds later, a jolt of the full stench would be fully noted by the olfactory center of my brain, engendering a primitive flight response, which I resisted. It smelled like the enclosed head of a small fishing vessel in which passengers had been seasick all night long as well as suffering from diverse intestinal ailments, and in which the flushing mechanism had finally broken. But that isn’t all: in that same unfortunate fishing vessel, a lower hatch recently had been pried open, revealing a horrific sight (and odor), a pile of forgotten herring that had been festering warmly for the last few months in a slippery pool of genuine bilge water.

I stood several feet from the table, building my courage. It did not help that the woman I was with, an expert on ancient Roman fish fermentations that essentially liquefy fish into a sauce called Garum, was not planning to taste surströmming. I said, “Really? Not even out of scholarly duty?” She was quite sure not!

The crowd had cleared so that I had a view of the bacterial fish remains set out invitingly on plates accompanied by Scandinavian flatbreads. The “pieces” of fish ranged from a sort of liquidy puddle to a clot of slime to something that had a bit of structure, albeit slumped. That latter gave me resolve, along with the fact that the samples were small (so as to provide enough for all).

I placed my surströmming on a fragment of flatbread and, well, I ate it. It was like a very complex cheese (that is, well-rotted milk) with a cascade of front flavors, middle flavors and then several layers of lingering surprises. It was intensely fishy along with being almost canonically cheesy: a fish-cheese. It reminded me of an excessively creative effort in marrying essential flavors by an ambitious young chef of a new fusion cuisine.

As for texture, the tiny bones had mostly decomposed, but a few remained for unexpected resistance. It was tolerable. It was not exactly “good,” but I could imagine myself in a situation (such as August in northern Sweden at a party, at which vodka was being served) of having more than one “piece.”

And, actually, Renee was right; if it were not for the smell, it would be just a notable morsel of very mature pickled herring. When others heard of my feat, they mentioned that I reeked of surströmming. And we were now back in the close, unventilated confines of the lecture hall. One person asked me if I was concerned that it could have gone bad and would there be any way of telling. The heartening news is that it is impossible for the bacterial culture that surströmming is to go bad. It is already there (having arrived many months ago) and there isn’t any room for further badness. Q

Professor Betsey Dyer’s research interests include symbiosis; termite symbionts; evolution of cells; field microbiology; and genomics. She is part of Wheaton’s Genomics Research Group, which is working on regulatory sequences of the genomes of eukaryotes.